Multiaxial force-torque sensors can be designed as a complex 3-dimensional transducer structure, with strain gauges placed in defined areas to measure strain, from which forces and torques can be calculated.
The transducer structure can include two concentric rings connected with spokes (3-4). In order to get information on all six axes (3 forces, 3 torques) and to achieve comparable sensitivity for all force and torque axes, strain gauges should be placed on different sides of the spokes, and partly also on the concentric rings.
The known transducer geometry can be highly complex, and can lead to a relatively large machining effort and consequently high cost. Additionally the application of the strain gauges to different sides of the spokes can only be made by handwork, which can take a long time and cause high cost.
Consequently, such sensors can be relatively expensive and this can limit their use to small volume special cost insensitive robot applications and to R&D (maximum 100 sensors of one type per year). Having a low cost multiaxial sensor available could extend the use of such sensors to large volume applications (several 100 to several 1000 sensors of one type per year), e.g. in robots, automotive, healthcare, etc.
Measuring three force and torque components with a planar mechanical structure using strain gauges placed on only one surface of the structure can be challenging. This is connected to symmetry properties of the structure.